A tissue-engineered body part is an amazing achievement. It is a medical advancement that could benefit many.
– Dr. Damon Noto
Regenerative medicine has offered us a glimpse of hope on organ regeneration. Scientists are able to grow new windpipes and urethras for patients by using their own stem cells. In Poland, dialysis patients received blood vessels grown from donated skin cells.
Now for the first time, doctors in Sweden have transplanted into the body of a 10-year-old girl a vein grown in the laboratory from her own stem cells.
The girl was suffering from a severe vein blockage to her liver. Treatment options available included a liver transplant, taking a vein graft from the umbilical cord of a donor, or a leg vein transplant from her own leg. However, the first two options would have led to permanent dependence on autoimmune drugs; the last option is associated with risks of lower limb disorders, and was not a good option due to the girl’s young age.
The doctors took a 9 cm section of vein from a deceased donor and removed all cells until only a hollow tube remained. The remaining tube was seeded with the girl’s stem cells (endothelial and smooth muscle cells) from the girl’s bone marrow. It took about 2 weeks of incubation period and the new blood vessel was transplanted into the patient.
Since the stem cells were the girl’s own, there was no adverse immune reaction and no autoimmune drugs needed. The only drawback is that 9 months after the procedure, the blood flow was decreased and a second lab-grown vein replacement was transplanted.
Scientist at the Yale University School of Medicine also built a heart blood vessel started from scratch in the lab and successfully transplanted it into a 4-year-old girl with a defected heart.
Instead of using a donor vessel, the doctors at Yale started with a tube made of biodegradable material that works as a scaffold to help stem cells grow tissue. On surgery day, the tube was seeded with the patient’s stem cells, which were taken the same day from the bone marrow in her hip. The stem cell scaffold was then implanted in the heart area where it will continue to grown. Eventually, the scaffold starts to degrade and new tissue starts to form.
The girl has been doing well after the transplant and since the blood vessel is made from her own cells, there is no problem of rejection. She will not experience the possible side effects caused by a synthetic graft either.
Another recent breakthrough in tissue engineering is that scientists are now at the beginning of growing a functioning liver. The researchers used stem cells from human skin cells and placed them on growth plates in a specially designed chemical bath. After 9 days of incubation, the cells started producing chemicals that a liver cell (hepatocyte) would produce. Two types of cells were then added into the medium: mesenchymal and endothelial, which are responsible for forming parts of blood vessels and structural tissues within the body.
In just two days, the cells assembled into a 5 mm long, three-dimensional lump, almost identical to an early stage of liver development- a liver bud. The tissue does not have bile ducts, but it has functional blood vessels when it was transplanted under the skin of a mouse. It is also able to metabolize some drugs that human livers metabolize but mouse livers normally cannot. Genetic testing revealed that the liver bud expresses many of the genes expressed in real liver.
This is the first time part of a functional human organ is produced using stem cells from human skin. Regenerative medicine opens up great possibilities for the organ-donor shortage.
Although future progress is needed before the above medical advancements can be widely adapted, we can certainly see the great promise of stem cell research. With enough dedication, it has the potential to change the world as we know it.